Zola draws attention to the new architecture that the railways engendered - the spacious halls of glass and steel at the Gare Saint-Lazare - and to the new mechanics of locomotive engineering. The novel conveys an exhilarating sense of what a journey by train in 1869 might have been like - the unprecedented speed of travel, the new experience of being whisked across rivers, carried over viaducts high above the landscape, rushed through tunnels and seeing whole towns pass by the window in less time than it takes to draw breath. The influence of the railways is suggested in more subtle ways: in the heightened sense of life being measured by the clock and even in the availability of certain sorts of food and drink - Roubaud’s Gruyère cheese and tin of sardines and Jacques’s bottle of Malaga wine. In ways such as these the railway is presented as the agent of change from the old to the new. The image of technological advance and material progress was one which the Second Empire, not without some justification, was happy to show to the world. Within the thematic topography of Zola’s novel, the railway as a symbol of progress stands at the opposite extreme to the atavistic killer instinct that dogs his central protagonist. This alignment of opposing principles underpins the whole novel.

But the novel also places question marks against the modernizing influence of the railway. Aunt Phasie can make little sense of the endless succession of trains that rushes past her window. The trains are crowded with people who seem to be in a great hurry to get somewhere, but she has little idea where they come from, where they are going to or what their purpose might be. Aunt Phasie cannot relate to the frantic pace and restless urgency of the world that the railway seems to typify. She is puzzled by the fact that each train that passes so close to her house contains more people than she has met in the whole of her life, yet she knows none of them and realizes that none of them are even aware of her existence. For Aunt Phasie the railway has created a disturbing sense of a world that is anonymous and depersonalized. The faces that pass by in the trains are ‘an indistinct blur, all merging into each other and all ending up looking alike’ (II). Even Jacques, her own adopted son, whom she looks out for every time his train goes by, comes and goes so quickly that she barely has time to return his wave. The same sense of anonymity and depersonalization lies behind Flore’s disregard for the innocent victims of the train crash she causes. Aunt Phasie’s reaction to the bright new future that the railway is said to be leading towards, in which ‘all the peoples of the world ... would soon be one big family’ (II), is one of scepticism. Her reaction is to a large extent a product of her own personal disappointments; whatever benefits the railway may have brought for others, none of them have come her way. But Aunt Phasie’s disenchantment is supported elsewhere in the novel by the image of the railway as a colossus stretching itself across the country, soulless and triumphant, ‘wilfully disregarding whatever shreds of humanity survived on either side of it’ (II), and even more forcibly by the image that ends the novel of a trainload of soldiers being carried out of control towards the carnage of war. Both of these images present the railway as a mechanical, inhuman and destructive force.

Alongside descriptions of the railway, which might be classed as objective representations of observed reality, there are descriptions which function as suggestive poetry. The first time the railway is mentioned in the novel it is described in terms of a physical assault on the city of Paris; the railway line and the station have been ‘gouged out’ (I) of the Quartier de l’Europe. Towards the end of the first chapter, as the night express on which Grandmorin will be murdered prepares to leave Paris, a mist gathers, and a damp chill fills the air. A red light pierces the darkness ‘like a splash of blood’. Shapes loom out of the mist. Sounds are heard - giant gasps of breath ‘like someone dying of a fever’ and sudden sharp whistles ‘like the screams of women being violated’ (I). At this point in the novel the reader has already heard of Grandmorin’s abuse of Séverine, has seen the violence of Roubaud’s reaction and has been alerted to an imminent act of murder. The sombre description of the railway station echoes the violence that has been perpetrated and intimates the violence that is to come. It offers an image of the world of darkness and confusion into which the novel is about to escort us. In general terms Zola presents the trains, undoubtedly with a degree of hyperbole, as monsters belching smoke and flames, passing by with the force of a hurricane, making the ground shake like an earthquake and deafening the world with their noise. Descriptions of this sort provide a running accompaniment to the violence that pervades the novel.